Wireless chipset with a non-temperature compensated crystal reference

ABSTRACT

An apparatus includes a temperature measuring device within a thermally conductive package. A crystal within the package is thermally coupled to the temperature measuring device and subjected to a same temperature as the temperature measuring device. A controller external to the package is configured to receive a signal from the crystal and a temperature measurement from the temperature measuring device. The controller is configured to estimate a frequency error of the crystal based on the temperature measurement and to provide a frequency error estimate to an external system.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of U.S. provisional patentapplication No. 61/442,513 in the names of WILCOX et al. filed on Feb.14, 2010.

TECHNICAL FIELD

The present description is related, generally, to electronics, morespecifically, to a wireless device for wireless communication

BACKGROUND

In a wireless communication system, a wireless device (e.g., a cellularphone) may transmit data to and receive data from a base station forbi-directional communication. For data transmission, the wireless devicemodulates outgoing data onto a radio frequency (RF) carrier signal andgenerates an RF modulated signal that is more suitable for transmissionvia a wireless channel. The wireless device then transmits the RFmodulated signal via a reverse link (or uplink) to the base station. Fordata reception, the wireless device receives an RF modulated signaltransmitted via a forward link (or downlink) by the base station. Thewireless device then conditions and digitizes the received signal toobtain samples and further processes the samples to recover the incomingdata sent by the base station.

The wireless device utilizes various local oscillator (LO) signals forfrequency upconversion and downconversion and various clock signals fordigital signal processing. The LO signals and clock signals may need tobe at precise frequencies in order to achieve good performance. Toobtain the required frequency precision, a temperature compensatedcrystal oscillator (TCXO) or a voltage controlled TCXO (VCTCXO) is oftenused to generate a reference signal having a frequency that iscompensated over a specified temperature range. The compensation isbased on a small number of discrete temperature values and is thus notvery accurate when those exact temperatures are not occurring. Thisreference signal is then used to generate the LO signals and clocksignals, which would then have the frequency precision of the referencesignal. However, the use of a TCXO or VCTCXO or a heating elementincreases design complexity as well as cost for the wireless device.Moreover, such solutions lack the resolution needed for accuracy over awide range of temperatures. In addition, the frequency error is notprovided to the overall system, but rather the compensated signal isprovided to the system. Accordingly, the system cannot act based on thefrequency error.

SUMMARY

According to some aspects of the disclosure, an apparatus includes atemperature measuring device within a package. One or more portions ofthe package are thermally conductive. The temperature measuring devicemeasures a temperature outside of the package. The apparatus alsoincludes a crystal within the package. The crystal is thermally coupledto the temperature measuring device and subjected to substantially thesame outside temperature. The apparatus also includes a controllerexternal to the package. The controller is configured to receive asignal from the crystal and a temperature measurement from thetemperature measuring device. The controller is also configured toestimate a frequency error of the crystal based on the temperaturemeasurement and to provide a frequency error estimate to an externalsystem.

According to some aspects of the disclosure, a method includes receivingat a controller external to a package, a signal from a crystal housedwithin the package. The controller also receives temperaturemeasurements from a temperature meeasuring device housed within thepackage. The crystal is thermally coupled to the temperature measuringdevice. The method also includes estimating a frequency error of thecrystal based on the temperature measurement. The method furtherincludes providing the frequency error estimate to an external system.

According to some aspects of the disclosure, an apparatus includes meansfor measuring temperature within a package. One or more portions of thepackage are thermally conductive. The temperature measuring meansmeasures a temperature that outside of the package. The apparatus alsoincludes a crystal within the package. The crystal is thermally coupledto the temperature measuring means and subjected to substantially thesame outside temperature. The apparatus also includes means forcontrolling an operation of the apparatus. The controlling means isexternal to the package. The controlling means includes means forreceiving a signal from the crystal and a temperature measurement fromthe temperature measuring means. The controlling means also includesmeans for estimating a frequency error of the crystal based on thetemperature measurement and means for providing a frequency errorestimate to an external system.

In another aspect, a computer program product for operating anon-temperature compensated crystal reference includes acomputer-readable medium having non-transitory program code recordedthereon. The program code includes program code to receive at acontroller external to a package, a signal from a crystal housed withinthe package, and temperature measurements from a temperature measuringdevice housed within the package. The crystal is thermally coupled tothe temperature measuring device. The program code also includes programcode to estimate a frequency error of the crystal based on thetemperature measurement. The program code further includes program codeto provide the frequency error estimate to an external system.

Additional features and advantages of the disclosure will be describedbelow. It should be appreciated by those skilled in the art that thisdisclosure may be readily utilized as a basis for modifying or designingother structures for carrying out the same purposes of the presentdisclosure. It should also be realized by those skilled in the art thatsuch equivalent constructions do not depart from the teachings of thedisclosure as set forth in the appended claims. The novel features,which are believed to be characteristic of the disclosure, both as toits organization and method of operation, together with further objectsand advantages, will be better understood from the following descriptionwhen considered in connection with the accompanying figures. It is to beexpressly understood, however, that each of the figures is provided forthe purpose of illustration and description only and is not intended asa definition of the limits of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present teachings, reference isnow made to the following description taken in conjunction with theaccompanying drawings.

FIG. 1 illustrates an example of a wireless device according to anaspect of the disclosure.

FIG. 2 shows a graph illustrating frequency deviation versus temperaturefor an AT-cut crystal.

FIG. 3 illustrates a schematic diagram of a crystal oscillator.

FIG. 4 illustrates a schematic diagram of an aspect of a temperaturemeasuring device.

FIG. 5 illustrates a thermally conductive package configured toaccommodate a crystal device and a temperature measuring deviceaccording to an aspect of the disclosure.

FIG. 6 illustrates a temperature compensation system according to anaspect of the disclosure.

FIG. 7 illustrates a signal processing method using a non-compensatedcrystal according to an aspect of the disclosure.

FIG. 8 is a block diagram showing an exemplary wireless communicationsystem in which an aspect of the disclosure may be advantageouslyemployed.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of variousconfigurations and is not intended to represent the only configurationsin which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing athorough understanding of the various concepts. However, it will beapparent to those skilled in the art that these concepts may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring such concepts.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any aspect or design described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other aspects or designs.

The wireless device described herein may be any electronics device usedfor communication, computing, networking, and other applications. Forexample, the wireless device may be a cellular phone, a personal digitalassistant (PDA), a wireless modem card, an access point, or some otherdevice used for wireless communication. The wireless device may also becalled a mobile station, a user equipment, a terminal, a subscriberunit, a station, or some other terminology.

The wireless device described, herein may be used for various wirelesscommunication systems such as a code division multiple access (CDMA)system, a time division multiple access (TDMA) system, a frequencydivision multiple access (FDMA) system, an orthogonal frequency divisionmultiple access (OFDMA) system, an orthogonal frequency divisionmultiplexing (OFDM) system, a single-carrier frequency division multipleaccess (SC-FDMA) system, and other systems that transmit modulated data.A CDMA system may implement one or more radio access technologies suchas cdma2000, Wideband-CDMA (W-CDMA), and so on. cdma2000 covers IS-95,IS-2000, and IS-856 standards. A TDMA system may implement Global Systemfor Mobile Communications (GSM). GSM and W-CDMA are described indocuments from a consortium named “3rd Generation Partnership Project”(3GPP). cdma2000 is described in documents from a consortium named “3rdGeneration Partnership Project 2” (3GPP2). 3GPP and 3GPP2 documents arepublicly available. An OFDMA system utilizes OFDM. An OFDM-based systemtransmits modulation symbols in the frequency domain whereas an SC-FDMAsystem transmits modulation symbols in the time domain. For clarity,much of the description below is for a wireless device (e.g., cellularphone) in a CDMA system, which may implement cdma2000 or W-CDMA. Thewireless device may also be able to receive and process GPS signals fromGPS satellites.

In addition, an OFDMA system may implement a radio

technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB),IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc,UTRA and E-UTRA are part of Universal Mobile Telecommunication System(UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are newreleases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSMare described in documents from an organization named “3rd GenerationPartnership Project” (3GPP). CDMA2000 and UMB are described in documentsfrom an organization named “3rd Generation Partnership Project 2”(3GPP2). The techniques described herein may be used for the wirelessnetworks and radio technologies mentioned above as well as otherwireless networks and radio technologies.

FIG. 1 shows a block diagram of an aspect of a wireless device 100 for aCDMA system. On the receive path, an antenna 110 receives one or more RFmodulated signals from one or more base stations and provides a receivedRF signal to a duplexer 112. The duplexer 112 filters the received RFsignal for a desired forward link frequency band and provides an inputRF signal to a receiver 122 within a transceiver 120. The desiredfrequency band may be cellular band from 824 to 894 MHz, PCS band from1850 to 1990 MHz, DCS band from 1710 to 1880 MHz, IMT-2000 band from1920 to 2170 MHz, or some other frequency band.

The receiver 122 amplifies and filters the input RF signal. The

receiver 122 may also implement a direct-to-baseband architecture or asuper-heterodyne architecture. In the super-heterodyne architecture, theinput RF signal is frequency down converted in multiple stages, e.g.,from RF to an intermediate frequency (IF) in one stage, and then from IFto baseband in another stage. In the direct-to-baseband architecture,the input RF signal is frequency downconverted from RF directly tobaseband in one stage. The following description assumes the receiver122 implements the direct-to-baseband architecture. In this case, thereceiver 122 frequency downconverts the input RF signal to baseband witha receive local oscillator (Rx_LO) signal. The frequency of the Rx_LOsignal is selected such that the signal in a desired CDMA channel isfrequency downconverted to baseband. The receiver 122 provides an analogbaseband signal containing the desired signal centered at or near DC.

Analog-to-digital converters (ADCs) 124 digitize the analog basebandsignal based on a sampling clock and provide ADC samples to a digitalfilter 152 within a digital section 150. ADCs 124 may be delta-sigmaADCs (.DELTA.. SIGMA. ADCs) as shown in FIG. 1, flash ADCs, or someother types of ADCs. A .DELTA..SIGMA. ADC can digitize an input signalwith few bits of resolution but at a sampling rate that is many timeshigher than the bandwidth of the signal. As a specific example,.DELTA..SIGMA. ADCs 124 may digitize the analog baseband signal withfour bits of resolution at approximately 32 times chip rate (orchip.times.32). The chip rate is 1.2288 megachips/second (Mcps) forcdma2000 and 3.84 Mcps for W-CDMA. These ADC samples may be subsequentlyprocessed to obtain output samples with 18 bits of resolution at thechip rate (or chip.times.1).

The digital filter 152 filters the ADC samples based on the samplingclock and provides filtered samples. The digital filter 152 may be afinite impulse response (FIR) filter, an infinite impulse response (IIR)filter, or some other type of filter. The digital filter 152 may alsoperform DC offset removal and/or other functions. A re-clocking circuit154 receives and re-clocks or re-samples the filtered samples based on adigital clock and provides data samples.

A receive (RX) digital rotator 156 frequency translates the data samplesto correct for frequency error in the downconversion process andprovides frequency-translated samples. A post-processor 158 may performautomatic gain control (AGC), digital filtering, sample rate conversion,and/or other processing on the frequency-translated samples and providesoutput samples. A rake receiver 160 performs demodulation on the outputsamples for one or more signal paths (or multiparas) and provides symbolestimates. A decoder (not shown in FIG. 1) may deinterleave and decodethe symbol estimates and provide decoded data.

On the transmit path, one or more processing units (not shown in FIG. 1)process data to be transmitted and provide data chips. A transmit (TX)digital rotator 176 frequency translates the data chips to compensatefor frequency error in the upconversion process and provides outputchips. Digital-to-analog converters (DACs) 178 convert the output chipsto analog and provide an analog output signal to a transmitter 142within the transceiver 120. The transmitter 142 amplifies and filtersthe analog output signal. The transmitter 142 also frequency upconvertsthe analog output signal to RF with a transmit LO (Tx_LO) signal andprovides an output RF signal. The frequency of the Tx_LO signal isselected such that the analog output signal is frequency upconverted toa desired CDMA channel. The duplexer 112 filters the output RF signalfor a reverse link frequency band and provides a filtered output RFsignal for transmission via antenna 110.

Although not shown in FIG. 1 for simplicity, many signals within thetransceiver 120 and digital section 150 are complex signals havinginphase (I) and quadrature (Q) components. Each processing unit mayprocess the I and Q components either separately or jointly depending onthe type of processing being performed.

A crystal oscillator (XO) 130 generates a reference signal having apredetermined frequency of f.sub.ref and good phase noisecharacteristics. As a specific example, the crystal oscillator 130 maygenerate a 19.2 MHz reference signal. The crystal oscillator 130 is notcompensated for temperature. Hence, the reference frequency f.sub.refdrifts with temperature and has a temperature dependent frequency error.An LO generator 132 receives the reference signal and generates theRx_LO and Tx_LO signals for the receiver 122 and transmitter 142,respectively. The LO generator 132 may include (1) a set of voltagecontrolled oscillator (VCO) and phase locked loop (PLL) that generatesthe Rx_LO signal for the receive path and (2) another set of VCO and PLLthat generates the Tx_LO signal for the transmit path. The VCO for eachpath generates a VCO signal having a frequency that may be varied by acontrol voltage. The PLL for each path generates the control voltagesuch that the VCO for that path is locked to the reference frequency.The Rx_LO or Tx_LO signal is then generated based on the VCO signal.Alternatively, the LO generator 132 may include a single set of VCO andPLL and mixing circuits that generate the Rx_LO and Tx_LO signals. Inany case, the frequency of the Rx_LO signal is determined by the CDMAchannel being received, and the frequency of the Tx_LO signal isdetermined by the CDMA channel to transmit on.

A divider 134 receives the Rx_LO signal and generates the samplingclock. As a specific example, the Rx_LO signal may be at twice thecellular band, and the divider 134 may divide the Rx_LO signal by afixed integer divider ratio of either 44 or 45 to generate the samplingclock at approximately 40 MHz. Since the frequency of the Rx_LO signalvaries depending on the CDMA channel being received, the sampling clockfrequency also varies with the received CDMA channel. However, thesampling clock has good phase noise characteristics because of the fixedinteger divider ratio.

A clock generator 170 receives the reference signal and generates thedigital clock. In an aspect, the clock generator 170 includes a VCO/PLLand a multi-modulus divider. The VCO/PLL generates an oscillator signalhaving a frequency that is some fixed integer multiple of the referencefrequency. The multi-modulus divider generates the digital clock basedon the oscillator signal. As a specific example, the VCO/PLL maygenerate a 384 MHz oscillator signal that is 20 times higher infrequency than the 19.2 MHz reference signal from the crystal oscillator130. The multi-modulus divider may generate a chip.times.32 clock basedon the 384 MHz signal. The chip.times.32 clock is 39.3216 MHz forcdma2000 and may be generated by dividing the 384 MHz signal by anon-integer divider ratio of 9.765625. The multi-modulus divider mayalso generate other clocks (e.g., a chip.times.16 clock) for otherprocessing units within the digital section 150. In another aspect, the

clock generator 170 includes (1) a VCO running at an integer multiple ofthe chip.times.32 clock and (2) a PLL having a multi-modulus dividerthat divides the oscillator signal by a non-integer divider ratio toobtain a feedback signal at the reference frequency. In any case, thedigital clock has a relatively accurate frequency that may be adjustedby changing the non-integer divider ratio. However, the digital clockhas undesired spectral components (or spurs) generated by thenon-integer divider ratio.

An automatic frequency control (AFC) unit 172 receives samples from therake receiver 160, estimates the frequency error based on these samples,and provides a frequency error estimate to digital rotators 156 and 176and the clock generator 170. The clock generator 170 adjusts itsoperation based on the frequency error estimate such that the digitalclock tracks chip timing.

A controller 180 controls the operation of various units within thewireless device 100. A memory 182 stores data and program codes for thewireless device 100.

FIG. 1 shows a specific aspect of the wireless device 100. In general,the processing for data transmission and reception may be performed invarious manners with various processing units. The transceiver 120 anddigital section 150 may include different and/or additional processingblocks not shown in FIG. 1. Furthermore, the processing blocks may bearranged in other manners. For example, the digital filter 152 may bepositioned after the re-clocking circuit 154 or after the digitalrotator 156.

Although not shown in FIG. 1 for simplicity, wireless device 100 mayinclude another receive path to process position location signals, suchas global positioning system (GPS) signals. The GPS receive path mayinclude all or many of the processing blocks in the CDMA receive path.However, the processing blocks for the GPS receive path may be designedspecifically for GPS and may operate at frequencies that are specificfor GPS. For example, the receive LO signal would be at a GPS frequency,the ADC may sample at a different rate, the digital filter may have adifferent bandwidth, and so on.

The wireless device 100 can provide good performance using a crystaloscillator that is not compensated for temperature, or simply, anon-compensated crystal oscillator. The wireless device 100 has thefollowing features:

-   -   Use of a “clean” sampling clock to digitize the baseband signal        by the ADCs;    -   Use of a digital clock with sufficient chip timing accuracy for        digital processing;    -   Use of a re-clocking circuit to go between the sampling clock        and the digital clock;    -   Use of a digital rotator on the receive path to correct for        frequency error in the frequency downeonversion process;    -   Use of a digital rotator on the transmit path to compensate for        frequency error in the frequency upconversion process;    -   Estimation of the frequency error of the crystal oscillator,        which is temperature dependent since the crystal oscillator is        uncompensated for temperature; and    -   Adjustment of the digital clock and the digital rotators in the        receive and transmit paths based on the frequency error        estimate.

These various features are described in detail below. The digital clockhas spurs that can degrade performance if used for sampling by.DELTA..SIGMA. ADCs 124. These spurs are generated by dividing anoscillator signal by a non-integer divider ratio that can vary overtemperature due to frequency drift in crystal oscillator 130. Thispotential degradation is avoided by using a sampling clock having goodphase noise characteristics for .DELTA..SIGMA. ADCs 124. This samplingclock is generated by dividing the Rx_LO signal by a fixed integerdivider ratio that does not change regardless of (1) the CDMA channelbeing received and (2) the frequency drift in crystal oscillator 130.This results in the sampling clock not being synchronized with thedigital clock. The re-clocking circuit 154 performs re-clocking of thesamples so that (1) ADCs 124 and digital filter 152 can operate based onthe sampling clock and (2) the digital rotator 156, post processor 158,rake receiver 160 and subsequent processing units can operate based onthe digital clock.

FIG. 2 shows plots of frequency deviation versus temperature for anexemplary AT-cut crystal. Different types of crystal cuts are available,and a popular cut for good frequency stability is the AT-cut. A crystalis cut such that it resonates at a desired nominal frequency (e.g., 19.2MHz) at room temperature (e.g., 23 degree Celsius). The resonantfrequency of the crystal varies across temperature based on a curve thatis dependent on the angle of the crystal cut. FIG. 2 shows the curvesfor seven different cut angles for an AT-cut crystal. Each curve showsthe deviation from the nominal frequency, in parts per million (ppm),across temperature for a specific cut angle.

The Crystal oscillator 130 may be designed such that its oscillationfrequency falls within a specified range. This covers the initialfrequency error for the crystal and frequency drift over temperature.For example, the specified range may be +−20 ppm to cover a crystalfrequency error of +−10 ppm and a temperature drift of +−10 ppm. In thiscase, the reference signal from crystal oscillator 130 may be off by asmuch as +−20 ppm from the nominal frequency.

For the aspect shown in FIG. 1, the reference signal from crystaloscillator 130 is used to generate (1) the Rx_LO signal used forfrequency downconversion, (2) the Tx_LO signal used for frequencyupconversion, and (3) the oscillator signal used to generate the digitalclock. The frequencies of the Rx_LO, Tx_LO, and oscillator signals arerelated to the reference frequency by some fixed ratios. Hence, an errorof X ppm in the reference frequency results in an error of X ppm in theRx_LO, Tx_LO, and oscillator frequencies. The frequency errors in theRx_LO, Tx_LO, and oscillator signals may be handled as described below.

FIG. 3 shows a schematic diagram of an aspect of the crystal oscillator130. For this aspect, the crystal oscillator 130 includes (1) a coarsetune control circuit that may be used for coarse frequency adjustmentand (2) a fine tune control circuit that may be used for fine frequencyadjustment.

Within the crystal oscillator 130, a crystal 310, a capacitor 316, and avariable capacitor (varactor) 318 couple in parallel and between theinput and output of an amplifier (Amp) 330. N-channel field effecttransistors (N-FETs) 312 a through 312 n have their sources coupled, tothe output of amplifier 330, their gates coupled to a control unit 340,and their drains coupled to one end of each of capacitors 314 a through314 n, respectively. The other end of each of capacitors 314 a through314 n couples to the input of the amplifier 330. The control unit 340receives a coarse frequency control signal and generates the controlsignals for N-FETs 312 a through 312 n. A resistor 320 has one endcoupled to the input of the amplifier 330 and the other end receiving afine frequency control signal. A buffer (Buf) 332 has its input coupledto the output of amplifier 330 and its output providing the referencesignal.

The amplifier 330 provides the signal amplification for oscillation.Crystal 310, capacitors 314 a through 314 n and 316, and varactor 318form a resonant circuit that determines the frequency of oscillation.N-FETs 312 a through 312 n act as switches that connect or disconnectthe corresponding capacitors 314 a through 314 n from the resonantcircuit. The buffer 332 provides buffering and signal drive for thereference signal.

The coarse tune control circuit includes N-FETs 312 a through 312 n,capacitors 314 a through 314 n, and control unit 340. Capacitors 314 athrough 314 n may have different capacitances that can vary theoscillation frequency by different amounts when connected. Capacitors314 a through 314 n may be selectively connected or disconnected basedon the coarse frequency control signal. For example, a 3-bit coarse tunecontrol circuit may be used to adjust the oscillation frequency byapproximately 5 ppm for each least significant bit (LSB) of control. Thefine tune control circuit includes the varactor 318 and resistor 320.The varactor 318 has a capacitance that can be adjusted based on thevoltage of the fine frequency control signal. For example, the fine tunecontrol circuit may provide a tuning range of +−10 ppm. The coarseand/or tune control circuits may be used to adjust the oscillationfrequency to account for known variations and/or for other purposes. Thecoarse and/or tune control circuits may also be omitted from the crystaloscillator 130.

FIG. 4 shows a schematic diagram of an aspect of a temperature measuringdevice 400. In some aspects of the disclosure, the temperature measuringdevice 400 can be a thermistor, for example, a thermistor chip. As shownin FIG. 4, a conventional thermistor chip 400 of this kind usually hasterminal electrodes 410 provided at both end parts of a thermistor block412 having, for example, an oxide of a transition metal such as Mn, Coand Ni as its principal component. The terminal electrodes 410 maycomprise an end electrode 410 a formed by applying Ag/Pd or the like ina paste form, for example, and then firing. In some aspects of thedisclosure, the terminal electrode may also include a plating layer 410b formed on its surface by using Ni or Sn, for example. The terminalelectrode may also include a middle layer, such as a Nickel-Copperlayer. The normal-temperature resistance value of such a thermistor chipis generally determined by the resistor value of the thermistor element412 and the position of the terminal electrodes 410.

Descriptions of the temperature measuring device are intended to beinterpreted broadly and are not limited to the exemplary thermistor 400.Many of the features of the aspects of the thermistor described abovemay be combined, whenever appropriate.

FIG. 5 illustrates a package configured to accommodate a crystal deviceor crystal, e.g., discrete quartz crystal, and a temperature measuringdevice, e.g., a thermistor. The package 500 includes a case 524 foraccommodating a crystal 502 and the temperature measuring device 504 andoutput electrodes 510 provided on an undersurface of the case 524. Insome aspects of the disclosure, the entire package 500 or at least someportions of the package 500 is thermally conductive. The case 524includes a first chamber or cavity 516 configured to accommodate thecrystal 502 and a second chamber or cavity 514 configured to accommodatethe temperature measuring device 504. The second chamber 514 can includea bottom wall 526.

The crystal 502 may be a discrete quartz crystal for generating areference frequency for a computer system or chipset. In some aspects ofthe disclosure, the crystal 502 may be used in conjunction with acircuit external to the thermally conductive package 500 to implement acrystal oscillator, e.g., the crystal oscillator 130 illustrated in FIG.3. The temperature measuring device 504 can be a discrete thermistor 400illustrated in FIG. 4. In some aspects of the disclosure, the package500 can be a ceramic package, where the ceramic package can be a dual Cor H configuration. The package 500 can be made of any material that haslow thermal resistance allowing for an accurate measurement of thecrystal temperature. In some aspects of the disclosure, a packageconstruction includes a base layer (not shown). The base layer may bethermally isolated from a circuit card assembly such that thetemperature measuring device 504 and the crystal 502 are thermallycoupled via a ceramic or other thermally conductive material. In someaspects of the disclosure, the crystal 502 can be placed in an upperchamber (upper C) and the temperature measuring device 504 can be placedin a lower chamber (lower C) of the ceramic package. The ceramicmaterial is configured to be mechanically robust to mechanically isolatethe crystal 502 from the movement on an electronic board or printedcircuit board. A high thermal conductivity ceramic material may beselected to increase/maximize the thermal coupling between thetemperature measuring device 504 and the crystal 502. The location ofthe temperature measuring device 504 may be selected to increase thecorrelation between the temperature of the crystal 502 and thetemperature measuring device 504.

The temperature measuring device 504 and the crystal 502 are thermallycoupled to each other and to the case 524 with a material having lowthermal resistance. The crystal 502 may be coupled through a conductivesubstrate 506 to an inner electrode 508 and supported in a cantileverstate. The inner electrode 508 may be linked to the outer electrode 510through a conductive line 512 wired on the thermally conductive package500. The temperature measuring device 504 may be connected through aconductive substrate 520 to an inner electrode 522, for example. Theinner electrode 522 may be linked to an outer electrode 510 on thethermally conductive package 500. A cover 518 that may be configured tohermetically seal the thermally conductive package 500 may enclose anopening to the crystal 502.

In some aspects of the disclosure, the first chamber 516 can be theupper chamber and the second chamber 514 can be the lower chamber. Thecrystal 502 and the temperature measuring device 504 can be accommodatedin either the upper chamber or the lower chamber. In some aspects, thefirst chamber 516 and the second chamber 514 are adjacent to each other.In some aspects, the crystal 502 and the temperature measuring device504 can be accommodated in the same chamber.

FIG. 6 illustrates a temperature compensation system according to anaspect of the disclosure. For explanatory purposes, FIG. 6 will bediscussed with reference to the above-discussed FIG. 5. The system 600includes a thermally conductive package 602, similar to the thermallyconductive package 500 of FIG. 5 and a controller 604, e.g., thecontroller 180 or any other controller or processor. The thermallyconductive package 602 can be a surface mounted package that is adaptedto be mounted on a surface of an electronic board or printed circuitboard 606. The controller 604 may also be configured for mounting on theelectronic board or printed circuit board 606.

A temperature measuring device, for example the temperature measuringdevice 504 of FIG. 5, in the thermally conductive package 602, can beconfigured to measure the temperature of its surroundings and totransmit a temperature measuring signal, indicating the temperature ofits surroundings, to the controller 604. Because the temperaturemeasuring device 504 is co-located in the same thermally conductivepackage 602 as the crystal device 502, the temperature reading of thetemperature measuring device 504 is substantially the same as thetemperature of the crystal 502.

In radio systems illustrated above, there is a clock source for acomputer system or chipset or the like. The clock source for someaspects may be 19.2 MHz, for example. Where the clock source is acrystal, such as the crystal 502. The crystal 502 generates a referencesignal having a predetermined frequency, e.g., 19.2 MHz. The crystal 502is not compensated for temperature. Hence, the reference frequencydrifts with temperature and has a temperature dependent frequency error.In some aspects, the crystal 502 is coupled to an oscillator located onan external chip, e.g., a power management integrated circuit (PMIC). Insome aspects, the oscillator may generate the reference signal, forexample at 19.2 MHz, rather than the crystal 502.

In some aspects, the controller 604 can be configured to executesoftware/firmware that compensates for the crystal frequency changesresulting from temperature in accordance with temperature measuringsignals generated by the temperature measuring device 504 and receivedat the controller 604. For example, the controller 604 may be configuredto receive temperature measurements from the temperature measuringdevice and to determine a temperature difference, to ascertain afrequency error difference based on the temperature difference. One ormore frequency slopes can be derived from the multiple temperaturemeasurements and multiple frequency slopes can be accumulated to derivea frequency error estimate. In some aspects, the accumulated frequencyslopes may be used to obtain a frequency change and to sum the frequencychange with an initial frequency value to obtain the frequency errorestimate.

In some aspects, the system 600 may include a rotator such as a rotator156 configured to receive data samples having the frequency error. Therotator 156 may also be configured to frequency translate the datasamples based on the frequency error estimate, and to providefrequency-translated samples.

In some aspects, the crystal 502 described herein, may replace atemperature compensated crystal oscillator of the computer system,chipset or the like. The discrete quartz crystal 502, for example, andthe temperature measuring device 504, for example, can be used inconjunction with a power management integrated circuit (PMIC) and aradio frequency interface chip (RFIC) or a baseband processor. Thecircuit external to the thermally conductive package, e.g., the PMIC,can be leveraged for the oscillator functionality. The radio frequencyinterface chip or baseband processor can be configured to executesoftware/firmware or a temperature compensation algorithm thatcompensates for the crystal frequency changes as a function oftemperature due to the third order polynomial behavior of the crystalfrequency output as a function of temperature. In some aspects, thetemperature compensation algorithm can be implemented according to thetemperature compensation method described in U.S. Patent ApplicationPublication No. 2007/0104298, the disclosure of which is expresslyincorporated by reference herein in its entirety.

FIG. 7 illustrates a signal processing method using a non-compensatedcrystal according to an aspect of the disclosure. This method may beimplemented in the temperature compensation system 600 illustrated inFIG. 6. At block 702, the process starts with receiving at a controllerexternal to a thermally conductive package, a signal from a crystal andtemperature measurements from a temperature measuring device. Thecrystal and the temperature measuring device are both housed within thethermally conductive package and thermally coupled together. One or moreportions of the package are thermally conductive. The process thencontinues to block 704 where the controller estimates a frequency errorof the crystal based on the measured temperature. At block 706, thecontroller provides the frequency error estimate to an external system,such as a power management IC, a radio frequency IC, and/or a basebandprocessor.

In one configuration, the apparatus includes means for measuringtemperature within the package. In one aspect of the disclosure, thetemperature measuring means may be the temperature measuring device 400and/or the temperature measuring device 504 configured to perform thefunctions recited by the temperature measuring means. In oneconfiguration, the apparatus includes means for means for controlling anoperation of the apparatus. In one aspect of the disclosure, thecontrolling means may be the controller 180 and/or the controller device804 configured to perform the functions recited by the controllingmeans.

FIG. 8 is a block diagram showing an exemplary wireless communicationsystem 800 in which an aspect of the disclosure may be advantageouslyemployed. For purposes of illustration, FIG. 8 shows three remote units820, 830, and 850 and two base stations 840. It will be recognized thatwireless communication systems may have many more remote units and basestations. Remote units 820, 830, and 850 include IC devices 825A, 825Cand 825B, which include the disclosed integrated temperature measuringdevice and crystal device. It will be recognized that other devices mayalso include the disclosed integrated temperature measuring device andcrystal device, such as the base stations, switching devices, andnetwork equipment. FIG. 8 shows forward link signals 880 from the basestation 840 to the remote units 820, 830, and 850 and reverse linksignals 890 from the remote units 820, 830, and 850 to base stations840.

In FIG. 8, remote unit 820 is shown as a mobile telephone, remote unit830 is shown as a portable computer, and remote unit 850 is shown as afixed location remote unit in a wireless local loop system. For example,the remote units may be mobile phones, hand-held personal communicationsystems (PCS) units, portable data units such as personal dataassistants, GPS enabled devices, navigation devices, set top boxes,music players, video players, entertainment units, fixed location dataunits such as meter reading equipment, or any other device that storesor retrieves data or computer instructions, or any combination thereof.Although FIG. 8 illustrates remote units according to the teachings ofthe disclosure, the disclosure is not limited to these exemplaryillustrated units. Aspects of the disclosure may be suitably employed inany device, which includes integrated temperature measuring device andcrystal device.

The methodologies described herein may be implemented by various meansdepending upon the application. For example, these methodologies may beimplemented in hardware, firmware, software, or any combination thereof.For a hardware implementation, the processing units may be implementedwithin one or more application specific integrated circuits (ASICs),digital signal processors (DSPs), digital signal processing devices(DSPDs), programmable logic devices (PLDs), field programmable gatearrays (FPGAs), processors, controllers, micro-controllers,microprocessors, electronic devices, other electronic units designed toperform the functions described herein, or a combination thereof.

For a firmware and/or software implementation, the methodologies may beimplemented with modules (e.g., procedures, functions, and so on) thatperform the functions described herein. Any machine or computer readablemedium tangibly embodying instructions may be used in implementing themethodologies described herein. For example, software code may be storedin a memory and executed by a processor. When executed by the processor,the executing software code generates the operational environment thatimplements the various methodologies and functionalities of thedifferent aspects of the teachings presented herein. Memory may beimplemented within the processor or external to the processor. As usedherein, the term “memory” refers to any type of long term, short term,volatile, nonvolatile, or other memory and is not to be limited to anyparticular type of memory or number of memories, or type of media uponwhich memory is stored.

The machine or computer readable medium that stores the software codedefining the methodologies and functions described herein includesphysical computer storage media. A storage medium may be any availablemedium that can be accessed by a computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to storedesired program code in the form of instructions or data structures andthat can be accessed by a computer. As used herein, disk and/or discincludes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer readable media.

In addition to storage on computer readable medium, instructions and/ordata may be provided, as signals on transmission media included in acommunication apparatus. For example, a communication apparatus mayinclude a transceiver having signals indicative of instructions anddata. The instructions and data are configured to cause one or moreprocessors to implement the functions outlined in the claims.

Although the present teachings and their advantages have been described,in detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the technologyof the teachings as defined by the appended claims. Moreover, the scopeof the present application is not intended to be limited to theparticular aspects of the process, machine, manufacture, composition ofmatter, means, methods and steps described in the specification. As oneof ordinary skill in the art will readily appreciate from thedisclosure, processes, machines, manufacture, compositions of matter,means, methods, or steps, presently existing or later to be developedthat perform substantially the same function or achieve substantiallythe same result as the corresponding aspects described herein may beutilized according to the present teachings. Accordingly, the appendedclaims are intended to include within their scope such processes,machines, manufacture, compositions of matter, means, methods, or steps.

1. An apparatus, comprising: a temperature measuring device within apackage, at least a portion of the package being thermally conductive,the temperature measuring device measuring a temperature of the package;a crystal within the package, the crystal being thermally coupled to thetemperature measuring device and subjected to substantially the sametemperature; and a controller external to the package, the controllerbeing configured to receive a signal from the crystal and a temperaturemeasurement from the temperature measuring device, the controller beingconfigured to estimate a frequency error of the crystal based on thetemperature measurement and to provide a frequency error estimate to anexternal system.
 2. The apparatus of claim 1, in which the packagecomprises a ceramic material.
 3. The apparatus of claim 1, in which thepackage and the controller are implemented on an electronic board. 4.The apparatus of claim 1, in which the package is configured toaccommodate the crystal in an upper cavity of the package and toaccommodate the temperature measuring device in a lower cavity of thepackage.
 5. The apparatus of claim 1, in which the temperature measuringdevice comprises a thermistor.
 6. The apparatus of claim 1, in which thepackage is configured in an H configuration.
 7. The apparatus of claim1, in which the package comprises a base layer thermally isolated from acircuit card assembly,
 8. The apparatus of claim 1, integrated into atleast one of a mobile phone, a set top box, a music player, a videoplayer, an entertainment unit, a navigation device, a computer, ahand-held personal communication systems (PCS) unit, a portable dataunit, and a fixed location data unit.
 9. A method comprising: receivingat a controller external to a package, a signal from a crystal housedwithin the package, and temperature measurements from a temperaturemeasuring device housed within the package, the crystal being thermallycoupled to the temperature measuring device; estimating a frequencyerror of the crystal based on the temperature measurement; and providingthe frequency error estimate to an external system.
 10. The method ofclaim 9, further comprising integrating the controller, crystal, andtemperature measuring device into at least one of a mobile phone, a settop box, a music player, a video player, an entertainment unit, anavigation device, a computer, a hand-held personal communicationsystems (PCS) unit, a portable data unit, and a fixed location dataunit.
 11. An apparatus, comprising: means for measuring temperaturewithin a package, at least a portion of the package being thermallyconductive, the temperature measuring means measuring a temperature ofthe package; a crystal within the package, the crystal being thermallycoupled to the temperature measuring means and subjected tosubstantially the same temperature; and means for controlling anoperation of the apparatus, the controlling means being external to thepackage, the controlling means comprising means for receiving a signalfrom the crystal and a temperature measurement from the temperaturemeasuring means, the controlling means comprising means for estimating afrequency error of the crystal based on the temperature measurement andmeans for providing a frequency error estimate to an external system.12. The apparatus of claim 11, in which the package comprises a ceramicmaterial.
 13. The apparatus of claim 11, in which the package and thecontrolling means are implemented on an electronic board.
 14. Theapparatus of claim 11, in which the package is configured to accommodatethe crystal in an upper cavity of the package and to accommodate thetemperature measuring means in a lower cavity of the package.
 15. Theapparatus of claim 11, in which the package comprises a base layerthermally isolated from a circuit card assembly,
 16. The apparatus ofclaim 11, in which the package is configured according to a dual Cconfiguration.
 17. The apparatus of claim 11, integrated into at leastone of a mobile phone, a set top box, a music player, a video player, anentertainment unit, a navigation device, a computer, a hand-heldpersonal communication systems (PCS) unit, a portable data unit, and afixed location data unit.
 18. A computer program product for operating anon-temperature compensated crystal reference, comprising: acomputer-readable medium having non-transitory program code recordedthereon, the program code comprising: program code to receive at acontroller external to a package, a signal from a crystal housed withinthe package, and temperature measurements from a temperature measuringdevice housed within die package, the crystal being thermally coupled tothe temperature measuring device; program code to estimate a frequencyerror of the crystal based on the temperature measurement; and programcode to provide the frequency error estimate to an external system, 19.The computer program product of claim 18, integrated into at least oneof a mobile phone, a set top box, a music player, a video player, anentertainment unit, a navigation device, a computer, a hand-heldpersonal communication systems (PCS) unit, a portable data unit, and afixed location data unit.